I owned (three) 16-50's and I still have the Tamron 17-50. The Tamron has significantly better uniformity of sharpness from edge to edge at all apertures. In sharpness, the 16-50 can't touch the 17-50. The 16-50 however, is a bit wider (but with noticeable "mustache" distortion), has SDM, and weather sealing.

I replaced the 16-45 with the Tamron and am generally happy with the Tamron. It is a stop faster, and it is a sharp lens. Still, this (16-45) is the only lens I have ever regretted selling, and, even though I have the range covered and am happy with the lens that is covering it, I wouldn't surprise myself if I bought another copy.

I know there is ongoing discussion of the Pentax 16-45 vs 16-50, but from what I read the Tamron 17-50 may hold its own (or outperform) either/or.

Setting aside any (unlikely) generalized bias in favor of Pentax lenses, does anyone have experience with the Tamron and either of the Pentax lenses that you could share?
Brian

Hi Brian:

Before I bought either my k20 or Tammy 17-50 I read and read, and read. In fact, it was in choosing these two little gems that I came to fathom the fruit of having done post graduate work where the degree was mostly obtained through voluminous reading.

What I am getting at is this: I tried to get my hands on every piece of pertinent information so that I would not regret my choices. I knew this was going to be expensive and I wanted to do it right. After finally ruling out the Nikon, Canon and Sony competitors to the K20, I then moved into my "walk-around" lens options.

Eventually, I narrowed down my choices to the three you posted in this thread. I then read, omnivorously, everything and everyone which shed light on the matter. I especially weighted reviews, by actual owners of the lenses, when possible, into the equation. It was not long before the Tamron lens began to stand out.

Discerning through the readings, it became clear the Tamron was the lens to be bought. Since then, I have never looked back. It is a fine performing lens and a good value when you consider all it does. It would be nice to see it in a weather-proofed form too.

In comparing the Tamron 17-50 and 28-75 to the DA* 16-50, the Pentax won out on sharpness, and really kicked ass on micro contrast/colour/not sure what you call it.

Even my new to photography girlfriend commented that the photos with the Pentax looked overall better than the Tamrons. We even ended up mixing and matching cameras and lenses between the K100D, K10D and K20D. (I bought the Tamron 17-50 for her mother, who I sold the K10D to, already owned the 28-75)

I think people get too hung up on sharpness only, that's not the only measure of a lens.

The Pentax does have some weird distortion issues though at 16mm, and softer corners. It's certainly not flawless.

It's hard to go past the Tamron's for value for money though, you get probably 90% of the image quality for a significantly less price. Of course, you lose SDM and weather sealing, but they might not be important to your photography style. I don't care about SDM much, but I do care about sealing.

In comparing the Tamron 17-50 and 28-75 to the DA* 16-50, the Pentax won out on sharpness, and really kicked ass on micro contrast/colour/not sure what you call it.

Even my new to photography girlfriend commented that the photos with the Pentax looked overall better than the Tamrons. We even ended up mixing and matching cameras and lenses between the K100D, K10D and K20D. (I bought the Tamron 17-50 for her mother, who I sold the K10D to, already owned the 28-75)

I think people get too hung up on sharpness only, that's not the only measure of a lens.

The Pentax does have some weird distortion issues though at 16mm, and softer corners. It's certainly not flawless.

It's hard to go past the Tamron's for value for money though, you get probably 90% of the image quality for a significantly less price. Of course, you lose SDM and weather sealing, but they might not be important to your photography style. I don't care about SDM much, but I do care about sealing.

This was pretty much my experience also after shooting with the Tamron for a week while I owned my 16-50. 16-50 had better colors and contrast, and better flare control. The Tammy was very, very good though, and I think I'd buy it over the 16-45 just for the f/2.8 alone. But the 16-50 was tops.

jesalonen
What happened to Sigma 18-50/2.8 Macro? It used to be a very nice lens, in Canon mount. Has fellow Pentaxians had problems with it? Just asking, 'cause I need something to replace my kit zoom, too.

I have heard good things about this lens too, but have heard little of it in Pentax mount. I met a professional photographer on the trails last August in Vermont, she had one of these mounted to her Canon 30d and was happy with it. It has a neat finish on it too which gives it a classy look.

I would like to hear more about this lens in Pentax mount if anyone can do this for us. Here are 84 reviews of the lens from the Miranda site: FM Reviews - 18-50mm F2.8 EX DC